DESCRIPTION: (Applicant's Abstract) This is a proposal to continue a study of the predisposing properties of tobacco for cocaine use to determine more precisely the developmental course of the tobacco-cocaine connection from adolescence through adulthood. This research involves completing a second interview of adults who have been participants since 1974 in a longitudinal study of ADHD and other childhood behavior problems. While it has been established that the use of tobacco temporally precedes use of illegal drugs, to our knowledge no research in humans has been conducted with a longitudinal sample that could assess the effects of pre-exposure to tobacco as sensitizing agent in the uptake and abuse of illegal drugs, most notably cocaine. Evidence from the animal literature, however, has demonstrated that pre-exposure to both nicotine and amphetamine compounds predisposes rates to the reinforcing impact of cocaine. Many participants in this study are both heavy tobacco smokers and/or have been treated with stimulant medications. Questions to be answered are: 1) What is the proportion of variance in frequency of usage and initial reaction to cocaine that can be attributed to tobacco pre-exposure? 2) Does the pattern and progression of drug used from adolescence through young adulthood differ in the ADHD and control groups? 3) Does the variability in diagnoses of drug abuse and dependence reflect reliable patterns of adult use within this sample or are differences attributable to inconsistencies among the diagnostic systems? 4) What differences are there in the cognitive reasoning process that underlie use of cocaine as compared to other drugs and among those with ADHD symptomatology as compared to their age-mate controls.